
def is_prime(n):
    if n < 2:
        return False
    for i in range(2, int(n**0.5)+1):
        if n % i ==0:
            return False
        return True


    print(is_prime(13))


    #递归阶乘
    def factorial(n):
        if n == 1:
            return 1
        else:
            return n * factorial(n-1)
